It is known in the molding business and particularly in the pipe molding business to use moving molds in forming the pipe for product. These moving molds are formed by mold block sections that mate with one another to define a mold block tunnel. Molten plastic is fed from an extruder into the moving mold tunnel. The mold block sections then separate from one another along what is known as a return run to move back to an up stream position for reentering the moving mold. The plastic product or pipe emerges from the downstream end of the moving mold where the mold block sections separate from one another before moving to their return path.
As the mold block sections move in a downstream direction in the moving mold tunnel they pick up a large amount of heat from the molten plastic. This is detrimental to the cooling and shaping of the product in the moving mold. As such, it is important to attempt as much as possible to cool the mold block sections. Typically, this is done while the mold block sections are mated with one another through the moving mold by subjecting them to different cooling mediums. One cooling medium according to conventional practice may be in the form of chilled water run through or onto the surfaces of the mold block sections. Another cooling medium is cooling air run through the mold tunnel.
In the case where water is used to cool the mold block sections there are generally problems created in controlling and drawing the water flow
In the case of introducing cooling air directly into the mold tunnel there are problems associated with the location for the introduction of the air to get it into the mold tunnel. Further there is a problem with cooling of the actual extrusion equipment through which the air is passed to get the air into the interior of the mold tunnel.